Sound amplifier



Sept. 20, 1927.

c. BLIEBERGER sounn AMPLIFIER Original Filed Feb. 19, 1923 2 Sheets-Sheet 1 P 7' c. BLIEBERGER 'sounn AMPLIFIER 2 Sheets-Sheet 2 Original Filed Feb. 19, 1923 Patented Sept. 20, 192 7.

UNITED STATES PATENT OFFICE.

CHARLES BLIEBERGER, OF NEW YORK, N. Y., ASSIGNOR F FORTY-FIVE PER GENT TO ADOLPH A. THOMAS, OF NEW YORK, N. Y.

SOUND AMPLIFIER.

Application filed February 19, 1928, Serial No. 619,826. Renewed April 27, 1926.

My invention is for a new and improved amplifier for use in phonographs, radio loudspeakers, and the like. The amplifier of my present invention is greatly superior to ordinary horns in quality of reproduction, and yet possesses suflicient volume, at the same time being compact in construction.

The objections to horns or megaphones as sound amplifiers aretoo well known to require explanation here. We are all familiar with the undesirable horny and harsh quality of sound issuing out of a horn.

Manufacturers of phonographs and radio loudspeakers have long been aware of these inherent drawbacks in horns and have resorted to various expedients in an endeavor to improve their tone quality.

In my prior Patents No. 1,425,505, dated August 15, 1922, and No. 1,436,080, dated November 21, 1922, I have set forth and claimed broadly sound-amplifying apparatus comprising a sound-receiving chamber and a plurality of sound com artments in communication with said cham er and open to the outer air. This causes a diffusion or distribution'of sound and results in a reproduction of improved tone quality, as I have repeatedly demonstrated.

In the present invention I make use ofthe foregoing principle to provide a construction particularly adapted to be easily substituted in phonograph and radio cabinets in place of the horns previously employed, and with practically no alterations in the partments around the member communicate embodiment shown in the accompanying cabinet itself. This ready installation of my I prises a diverging sound-conveyin member with the free air. In this way, the sound waves issuing out. of the conveying memher and those issuing out of the surroundmg space or compartments pass'into the free air through the usual 0 ening in the front wall of the cabinet. T is eliminate! the necessity of providing sound outlets in the sides or corners of the cabinet, and permits installationof the invention in cabinets of prior or'standardized design.

My present invention is also applicable to horns which are not enclosed 'in boxes or. cabinets,for instance, horns in radio loudspeakers. The tone quality of such horns is greatly improved by providing them with lateral sound openings and mounting vibratory panels over the openings, the panels being spaced from the walls of the horn. These panels may be mounted inside or outside of the horn; or, some of the panels may be inside and others outside of ithehorn.

In order to explain my invention, so that those skilled in the art may construct and. use the same, I shall describe in detail the 78 drawings, irf which Fig. 1 1s a top plan vlew in cross-section,

I approximately on line 11 of Fig. 2, showing a form of my new sound amplifier en cased in a phonograph cabinet;

Fig. 2 is a vertical cross-sectionapproximately on line 2-2 of Fig. 1, looking in the direction of the arrows and showing a; side view of the amplifier;

Fig. 3 is a cross-section approximately on the broken line .33 of Fig. 1, the cabinet being omitted for the sake of clearness; and

Fig. 4 is a front view of the amplifier shown in the preceding figures.

In Figs. 1 and 2, there is a cabinet indicated as a whole by C, which in this instance is a phonograph cabinet of suitable design and proportions. Any kind of box or cabinet may be used to enclose the amplifier. Within the chamber 1 of cabinet C is mounted a sound-conveying member indicated asa whole by S. This member, which has the general shape of a horn, consists of walls 2, 3, 4 and 5. These walls extend rearwardly and-upwardly to forma throat or passage 6, which is open at 7 to permit communication with the tone arm 8 or with any suitable source of sound to be amplified.

In the drawings, the horn S is of rather peculiar design, and is arranged obhquely within the cabinet. This articular shape and arrangement is merely mcidental, and is for the sole purpose of accommodating the tone arm 8 in proper position with the respect to the turntable 9 of the phonograph. The sound chamber or horn S may be made symmetrical or in any other desired shape, depending upon the size, style and proportion of the particular cabinet in which the horn is to be enclosed.

The walls of the horn S are provided with sound openings 10. In the drawings I have shown two openings in each wall, and these openings run generally in an axial direction, diverging toward the mouth of the horn. It should be understood, however, that the number, shapeand arran ement of the openings may vary in accor ance with the size and shape of the horn. Also, the particular acoustic efiect desired to be produced may be a factor in regard to the openings 10. I may also provide openings in the corners of the walls, and some of the openin s may converge toward the mouth of the horn, while others may converge in the opposite direction. I mention this merely as illustrative of the changes that may be resorted to.

Over the openings 10 in the walls S are mounted panels 11, 12, 13 and 14. These panels are preferably, but not necessarily, secured to the walls of the horn by an .suitable means, such as screws or b0 ts 15. Sleeves or bushings 16 hold the panels properly spaced from their respective walls, so as to form sound chambers or spaces 17 between the horn and the panels. Personally I prefer to mount the panels obliquely with respect to the walls of the horn, so as to make the sound chambers pyramidal or diverging. The shape of the panels 11, 12, 13 andli will, of course, depend on the shape of the horn and also upon the size, shape and arrangement of the sound 0 enings 10. As shown in Fig. 2, the panel 13 is cutaway at 18 to accommodate the motor- M of the phonograph.

The panels 11, 12, 13 and 14'are preferably of wood and sufliciently thin to be vibratory under the action of sound waves. The spacing members 16 may be of suitable soundabsorbing material, such as rubber, leather,

felt and the like, although that is. not absolutely necessary. Althou h I have shown the panels mounted outsi e the born, I may mount them on the inside. In fact, some of the panels may be supported outside the horn and others inside. So when I say that I the ]panels are mounted, over the openings 10, mean broadly that they are arranged across the openings, whether inside or outside the horn.

The box or cabinet C hasa frontopening 19 at which the mouth of the horn S terminates. In ractice the mouth of the horn is practical y coextensive with the opening 19. When I refer to the opening 19 as a front opening, I .use the expression merely in a' relative sense; The outer edges of the walls 2, 3, 4 and 5 of'amplifying member S are cutaway, as indicated at 20. The purpose of thecutaway portions 20 is to provide sound outlets between. the space or chambers around the horn S and the free outer air. In Fig. 4, these soundoutlets are indicated at 21. In the construction illustrated in the drawings, the sound outlets 21 are formed bycutting away the outer edge of the horn S in an oblique direction. However, that is not necessary, and I would have it understood that communication between the free air and the sound chambers surrounding the amplifier S may be established in any other suitable way.

In the operation of my new amplifying device, as the sound waves enter the horn S at the smaller end thereof, they pass in part through the openings 10. The impact of the sound waves against the panels 11,12, 13 and 14 will cause the same to vibrate if they are of a vibratory material. In any event, the air in the spaces or chamber 17 between the horn and the panels is set in vibration and the wavesspread in partinto the spaces or chambers formed between the horn and the walls of the enclosing box or cabinet. From the sound chambers surrounding the horn,

the sound waves pass into the outer air through the outlets 21. The opening 19 of the cabinet is thus a common outlet for the sound waves enteringthe neck of the horn. Some or a part of the waves entering the horn will pass directly through the born into the outer air,-while a portion of the waves will pass through the openings '10 and reach the outer air through the outlets 21. The proportion of sound waves passing through the openings 10 will depend mainly upon the size, shape and arrangement of theopenings.

Although I have referred to thesound conveying member S as a horn, I use the term merely forconvenience. As a matter 'ectionable acoustic properties of horns as eretofore constructed. It is a matter of common knowledge among those skilled in the art that prdinary horns, such as are found in prior phono ra hs andradio loudspeakers, give adecided y unnatural reproduction, which is commonly referred to as horny. For instance, the characteristic horny sound 'of a phonograph is recognizable even at a distance. According to my present nvention, I can utilize a horn as of fact, the member S has none of the obheretofore constructed-say, vfor instance, the horn of a standard make of phonographand embody therein the features of my invention as above explained. No changes in the outside of the cabinet are necessary, my construction being substituted for the old horn in the same space previously occupied by that horn. This ready substitution of my invention for the old types of horn is an important factor from a commercial standpoint, for it enables manufacturers of sound-reproducingapparatus to maintain their standardized form of cabinet.

To cite an instance of the practical application "of my invention, I took the horn out of a standard and widely known make of phonograph, utilized the horn in constructing my invention, and replaced the new con struction in the cabinet without any visible changes in the appearance of the cabinet. Actual tests demonstrated that the reproduction given by my new amplifier had a 1tone quality far superior to that of the old In general, I may say that my new sound amplifier does away with the harsh and choky reproduction of horns, and produces tones distinguished by a clear and natural quality. v'Thevolume of the reproduced sounds depends upon the characteristics of the vibrations that enter the amplifier and, upon the general shape and size of the device, and perhaps also upon other minor factors. A

In the broader aspect of my invention, the amplifying member S need not be encased in abox or cabinet. For instance, in the smaller types of radio loudspeakers, my new amplifier may be supported in an upright position on a suitable base, without being enclosed in a box.

Although I have herein shown and described a certain specific construction, I would have it understood that I have done so merely to explain my invention so as to enable those skilled in the art topractise the same, and not byway of limitation or restriction. It is obvious that the underlying idea of my invention may be mechanically carried out in other ways than herein set forth.

I claim as my invention:

1. A sound-amplifier comprising walls arranged to form a substantially pyramidalsound chamber adapted to be connected with source of sound, said wails being provided with sound openings, and vibratory panels arranged over said openings and spaced from said walls, said panels extending alon said walls in the general direction thereor and permitting escape of sound waves iaterally into the free air.

2. A sound-amplifier comprisin walls arranged to term a diverging soon chamber,

said walls being provided with sound openings, and vibratory panels secured to said walls opposite said openings and spaced from said walls, said panels extending along said walls in the general direction thereof and permitting escape of sound waves laterally into the free air.

3. A sound-amplifier comprisinga horn provided with elongated lateral sound openings extending generally lengthwise of the horn and panels arranged over said openings, said panels being spaced from the horn to provide sound chambers open to the free air.

4. A sound-amplifier comprising a horn provided with lateral sound openings and with panels arranged over said openings, said panels being secured to and spaced from the horn to provide sound chambers open to the free air.

5. A sound-amplifier comprising a box or cabinet having an opening in its outer wall,

an outwardly diverging sound-conveying membermounted in said cabinet so that the mouth of said member terminates substantially at the outer opening of the cabinet, there being a space between the walls of said cabinet and'the walls of said member to form sound chambers, said member being provided with lateral openings through which sound waves pass into said chambers, and means whereby said chambers communicate with the free air through said outer opening in the cabinet.

6. A sound-amplifier comprising a box or cabinet having an opening in its outer wall, an outwardly diverging sound-conveying member mounted in said cabinet so that the mouth of said member terminates substantially at the outer opening of the cabinet, there being a space between the walls of said cabinet and the walls of said member to form sound chambers, said member being provided with lateral openings through which sound waves passinto said chambers, and sound outlets at the outer end of said member for placing said chambers in communication with the free air.

7. A sound-amplifier comprising a box or cabinet having an opening in its outer walls, an outwardly diverging sound-conveying member mounted in said cabinet so that the mouth of i said member terminates substantially at the outer opening of the cabinet, there being a space between the walls or said cabinet and the walls out saidmember to form sound chambers, said member being provided with lateral openings through which sound waves pass into said chambers, the outer edge oi said member being cut away to provide sound outlets between said chambers and the free air. a

8. A sound-amplifier comprising a box or cabinet having an opening in its outer wall,

i there being a an outwardly diverging sound-conveying member mounted in said cabinet so that the mouth of said member terminates substantially at the outer opening of the cabinet, there being a space between the walls of said cabinet and the walls of said member to form sound chambers, said members being provided with lateral opening; through which sound waves pass into said chambers, vibratory panels arranged over said lateral openings'and spaced therefrom, and sound outlets at the outer end of said member for placing said chambers in communication with the free air.

9. A sound-amplifier comprising a box or cabinet having an opening in its outer walls, a sound-conveying member mounted in said cabinet so that the mouth of said member terminates substantially at the outer opening of the cabinet, there being a space between the walls of said cabinet and the walls of said member to form sound chambers, said member being provided with lateral openings through which sound wave; pass into said chambers, the outer edge of said memher being cut away to provide sound outlets between said chambers and the free air, and panels mounted over said lateral openings and spaced from the walls of said member.

10. A' sound-amplifier comprising a box or cabinet having an opening in its outer wall, an outwardly diverging sound-conveying member mounted in said cabinet so that the mouth of said member terminates substantially at the outer openin of the cabinet, space between t e walls of said cabinet and the walls of said member to form sound chambers, said member bein provided with lateral openings throng which sound waves pass into said chambers,

panels arranged in said chambers opposite said lateral openings and spaced from said 0 enings, and sound outlets at the outer end 0 said member for placing said chambers in communication with the free air.

11. A sound-amplifier comprising a box or cabinet having an opening in itsouter wall, a sound-conveying member mounted in said cabinet so that the mouth of said member terminates substantially at the outer opening of the cabinet, there being a space between the walls of saidcabinet and the walls of said member to form sound chambers, said member being provided with lateral openings through which sound waves pass into said chambers, vibratory panels arranged over said lateral openings and spaced therefrom, and means whereby said chambers communicate with the free air through said outer opening in the cabinet.

12. A sound-amplifier comprising a box or cabinet having an opening in its outer wall, an outwardly dlvergin sound-conveymember mounted in sai cabinet so. that sound-amplifier comprising walls SOUDd-TGCQIVIHg chamber source of sound, other walls arranged to form sound compartments around said chamber, there being openings through which said chamber communicates laterally with said compartments, and panels mounted over said openings and spaced therefrom, said chamber and said compartments being open to the free air.

14. A sound-amplifier comprising walls arranged to 'form a sound-receiving chamber adapted to be connected with a source of sound, other walls arranged to form sound compartments around said chamber,

there being openings through which said chamber communicates laterally with said compartments, and panels mounted on said first mentioned walls over said openings and spaced from said walls, said chamber and said compartments being open to the free air.

15. A sound-amplifier comprising walls arranged to form a sound chamber adapted to be connected with a source of sound, said walls being provided with sound openings, and panels arranged over said openings and spaced from said walls, said panels approximately paralleling and extending along said walls in the general direction thereof and permitting escape of sound waves laterally into the free air.

16. A sound-amplif er comprising ahorn provided with elongated sound openings extending generally lengthwise of the horn and panels arranged over said openings, said panels being spaced from the horn to provide a soundchamber open to the free air.

17. A soundamplifier comprising walls arranged to form a sound chamber adapted to be connected with a source of sound, certain of said walls being provided with a sound opening, and panels positioned over said openings and spaced from said walls permitting the escape of sound waves into the free air, said panels paralleling said walls and extending in the general direction thereof. I

18. A sound-amplifier comprising walls arranged to form a sound chamber and adapted to be connected with a source of sound, certain of said walls being provided with a sound opening, and means ositioned adapted to be connected with a source of over said openings and spaced rorn said sound, certain of said walls each being pro- 1 walls permitting the escapev of sound waves vided with at least one elongated sound into the free air, said means approximately opening extending generally lengthwise of 5 paralleling said walls and extending in the the horn and means cooperating with said general direction thereof. openings permitting the escape of sound 19. A sound-amplifier comprising walls waves into the free air. arranged to form a sound chamber and CHARLES BLIEBERGER, 

